/*
 * Copyright 2002-2018 the original author or authors.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      https://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package org.springframework.web.method.annotation;

import java.util.Collections;
import java.util.List;

import org.springframework.lang.Nullable;
import org.springframework.util.Assert;
import org.springframework.util.ObjectUtils;
import org.springframework.web.bind.WebDataBinder;
import org.springframework.web.bind.annotation.InitBinder;
import org.springframework.web.bind.support.DefaultDataBinderFactory;
import org.springframework.web.bind.support.WebBindingInitializer;
import org.springframework.web.context.request.NativeWebRequest;
import org.springframework.web.method.HandlerMethod;
import org.springframework.web.method.support.InvocableHandlerMethod;

/**
 * Adds initialization to a WebDataBinder via {@code @InitBinder} methods.
 *
 * @author Rossen Stoyanchev
 * @since 3.1
 */
public class InitBinderDataBinderFactory extends DefaultDataBinderFactory {

    private final List<InvocableHandlerMethod> binderMethods;


    /**
     * Create a new InitBinderDataBinderFactory instance.
     *
     * @param binderMethods {@code @InitBinder} methods
     * @param initializer   for global data binder initialization
     */
    public InitBinderDataBinderFactory(@Nullable List<InvocableHandlerMethod> binderMethods,
                                       @Nullable WebBindingInitializer initializer) {

        super(initializer);
        this.binderMethods = (binderMethods != null ? binderMethods : Collections.emptyList());
    }


    /**
     * Initialize a WebDataBinder with {@code @InitBinder} methods.
     * <p>If the {@code @InitBinder} annotation specifies attributes names,
     * it is invoked only if the names include the target object name.
     *
     * @throws Exception if one of the invoked @{@link InitBinder} methods fails
     * @see #isBinderMethodApplicable
     */
    @Override
    public void initBinder(WebDataBinder dataBinder, NativeWebRequest request) throws Exception {
        for (InvocableHandlerMethod binderMethod : this.binderMethods) {
            if (isBinderMethodApplicable(binderMethod, dataBinder)) {
                Object returnValue = binderMethod.invokeForRequest(request, null, dataBinder);
                if (returnValue != null) {
                    throw new IllegalStateException(
                            "@InitBinder methods must not return a value (should be void): " + binderMethod);
                }
            }
        }
    }

    /**
     * Determine whether the given {@code @InitBinder} method should be used
     * to initialize the given {@link WebDataBinder} instance. By default we
     * check the specified attribute names in the annotation value, if any.
     */
    protected boolean isBinderMethodApplicable(HandlerMethod initBinderMethod, WebDataBinder dataBinder) {
        InitBinder ann = initBinderMethod.getMethodAnnotation(InitBinder.class);
        Assert.state(ann != null, "No InitBinder annotation");
        String[] names = ann.value();
        return (ObjectUtils.isEmpty(names) || ObjectUtils.containsElement(names, dataBinder.getObjectName()));
    }

}
